SUBSTITUENT INFLUENCE ON THE FLUORESCENCE-SPECTRA OF 2,3-DIPHENYLBENZO[B]FURAN DERIVATIVES

The position and intensity of the emission band for 2,3-diphenylbenzo[ b]furans 1-16 and phenanthrobenzofurans 17-22 are affected by the natu re and position of the substituents, particularly, by those which exte nd the conjugated system. The major structural factors responsible for the augmentation of the fluorescence quantum yield and the displaceme nt of the fluorescence spectra towards the longer wavelengths, include considerable lengthening of the conjugation system and the electron-d onor behaviour of the substituents which upset the distribution of ele ctron density in the molecules of the compounds under study. (C) 1998 Elsevier Science B.V. All rights reserved.